As a layman, completely removed from the medical community, I thought that (myth) the Blue Blood/Red Blood immediate transformation was quite astonishing after we heard of it the other day, so astonishing in fact that my son decided to test it out in his science project. Now that we have read more about the myth I agree with your observation. Somewhere along the way, people began thinking that there was blue blood because of the combination of the anatomical drawings and the blue color of the veins below our skin. I even understand that they inject blue latex into cadaver's arteries. I'm sure this may also perpetuate the myth.

It reminds me a bit, but not to the same degree, of the consternation Benjamen Franklin inadvertently caused throughout the physics and electrical engineering communities when he named the positive and negative electrical charges backwards, although he had logical reasons for doing it that way. Electricity was all just fine until J.J. Thompson discovered the electron about a hundred years after Franklin. Now, everything in electricity, still to this day, is depicted backwards. Now every physicist has to think about electron flow in an opposite way. Today, a layman could study a simple electrical schematic and easily deduce that an electron moves in the opposite direction that it actually does, all because of a decision Benjamin Franklin made some 250 years ago. Unfortunately we're stuck with negative electrons for eternity!

It seems as though we're unable to get things absolutely right on the first pass, at least most of the time. Murphy's Law I suppose. If a bolt can be screwed on backwards, it eventually will be. How many aircraft accidents have we had while trying to learn that. We get stuck in the ruts of tradition, I'm sure if we could go back in time, with the knowledge we have today, we wouldn't depict arteries as blue and we would give the electron a positive charge.

And as a funny coincidence, I ran a gel electrophoresis sample the other day (a very basic procedure in molecular biology), and I was being a bit absent-minded and managed to connect the electrodes in a wrong way - and because the electron flow goes to the "opposite way" than what one would quickly think it caused my samples to run backwards on the gel.